Refractometer



FIG. 1 is a front perspective view of our new design for a refractometer;

FIG. 2 is a left side elevation view thereof;

FIG. 3 is right side elevation view thereof;

FIG. 4 is a back side elevation view thereof;

FIG. 5 is a front side elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom view thereof. 

The ornamental design for a refractometer, as substantially shown and described. 